Background infoMost Canon firmware upgrades were usually minor (like fixing a typo in the Ukrainian language), so upgrading ML to latest firmware was pretty easy. Not so with 5D3 1.2.3.

Most important changes in 1.2.3 since 1.1.3 (source):- clean HDMI out- dual monitor support- AF at f/8 with teleconverters- fixed an AFMA bug- a bunch of minor fixes

Unfortunately, in order to implement the dual monitor feature, Canon made some major changes on the display side (changed some low-level registers) and LiveView implementation (which is now quad-buffered, while on 1.1.3 it's triple-buffered, just like in all other ML-enabled cameras). From ML's point of view, this resulted in the following differences:

- 1.1.3 is slightly faster when recording RAW/MLV (not much, only a few MB/s)- fast zebras are not working on 1.2.3 or later, but they are OK on 1.1.3- no full-screen magic zoom on 1.2.3 or later- no brightness/contrast/saturation adjutments on 1.2.3 or later- "DIGIC peaking" is a little more limited on 1.2.3 or later (only the basic mode is working, not the ones with fancy backgrounds)- motion detection in "frame difference" mode does not work on 1.2.3 or later- I'm not sure if corrupted frames are still an issue (if you experience them, try downgrading to 1.1.3)

Other than that, the two ML versions are pretty much identical.

Bottom line:- if you need any of Canon's updates from firmware 1.2.3 or later, use 1.2.3 (and prepare for upgrading to 1.3.3)- otherwise, consider downgrading to 1.1.3 (I did).

Note: the upgrade from 1.2.3 to 1.3.3 was a minor one, and porting ML is straightforward (chris_overseas already did it, I only need to sit down and try it).

I know, maintaining two firmware versions for a single camera is a hassle, but if we want to squeeze the last drops of performance from this camera, we have no choice. And, as you've guessed, fixing some of the above issues is quite hard.

Please discuss raw recording issues in the Raw Video section of the forum, not here.

I second that @Quentin (love the crop-mode h.264 on the M) but not sure if it'll ever be possible on 5D3 because I think I may have remember someone mentioned awhile ago that it could be a hardware limitation regarding the FF sensor?

I second that @Quentin (love the crop-mode h.264 on the M) but not sure if it'll ever be possible on 5D3 because I think I may have remember someone mentioned awhile ago that it could be a hardware limitation regarding the FF sensor?